No evidence for preservation of somatostatin-containing neurons after intrastriatal injections of quinolinic acid

Abstract

BEAL ET AL. REPLY-Davies and Roberts contend that quinolinic acid striatal lesions do not spare somatostatin (NADPH-diaphorase) neurons. We have attempted to resolve the discrepancy by carefully re-examining our own material. There is one major methodological difference between the two reports. Davies and Roberts examined regions containing the lesion cores in which there is almost total neuronal loss and marked gliosis as depicted in their Fig. 1 and the data given in Fig. 2a. They found no selective sparing of neurons within this region and our own findings are in agreement with that result. Since we believe that sparing of somatostatin neurons is relative and not absolute, we make our counts in regions posterior to the lesion, where there is a depletion of total Nissl-stained neurons in the range of 50%. Within this region we find significant increases in NADPH-diaphorase neurons relative to acetylcholinesterase neurons. We have further examined this issue by counting numbers of NADPH-diaphorase neurons relative to the total number of Nissl-stained neurons. NADPH-diaphorase neurons are significantly increased as a percentage of the total neuronal population in this area. These results areconsistent with the findings of Choi and colleagues who showed that quinolinic acid results in relative, but not absolute, sparing of NADPH-diaphorase neurons in cortical cell cultures (Science 234, 73-76; 1986). © 1987 Nature Publishing Group.